Solid-state imaging systems or imaging readers have been used, in both handheld and/or hands-free modes of operation, to electro-optically read targets, such as one- and/or two-dimensional bar code symbols, each bearing elements, e.g., bars and spaces, of different widths and reflectivities, to be decoded, as well as fields in forms, such as documents, labels, receipts, signatures, drivers' licenses, identification badges, and payment/loyalty cards, etc., in retail stores, warehouses, distribution centers, libraries, and myriad other businesses.
A known exemplary imaging reader includes a housing either held by a user and/or supported on a cradle, stand or like support, a window supported by the housing and aimed at the target, and an imaging engine or module supported by the housing and having a solid-state imager (or image sensor) with a sensor array of photocells or light sensors (also known as pixels), and an imaging lens assembly for capturing return light scattered and/or reflected from the target being imaged through the window over a field of view, and for projecting the return light onto the sensor array to initiate capture of an image of the target over a range of working distances in which the target can be read. Such an imager may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device and associated circuits for producing and processing electrical signals corresponding to a one- or two-dimensional array of pixel data over the field of view. These electrical signals are decoded and/or processed by a programmed microprocessor or controller into information related to the target being read, e.g., decoded data indicative of a symbol, or characters or marks indicative of text in a field of a form, or into a picture indicative of graphics in a field of the form. If the target is a symbol associated with a retail product, then the decoded signal identifies the product and is transmitted to a host, e.g., a cash register or computer in, or remote from, a retail venue, for further processing, e.g., product price look-up or product inventorying.
In the handheld mode, the user may first lift the reader from a countertop or a support stand or cradle, and then hold the reader in his or her hand at a certain distance away from the target to be imaged, and then aim the reader at the target. Aiming has typically been performed either by having a user physically sight the target by viewing along a raised mechanical sighting element on the reader housing, or by having the user position the target relative to an aiming light pattern or mark projected onto the target by an on-board aiming light generator. A trigger is typically manually actuated by the user to initiate reading. Once reading is completed, the user may return the reader to the countertop or to the support stand to resume hands-free operation. An on-board beeper provides audio feedback of a successful read of the target. The beeper is an electroacoustic transducer that converts electrical energy into mechanical energy to emit a single audible beeping tone, or a plurality of the same beeping tones, when the target has been successfully read.
Although the known imaging readers are generally satisfactory for their intended purpose, one concern relates to the aiming process. A mechanical sighting element is not that accurate. An aiming light generator is costly, and adds extra electrical energy consumption, weight and size to the reader. Sometimes, the projected aiming light pattern is annoying and bothersome to the user, or to others in the vicinity of the reader. Sometimes, the projected aiming light pattern is not readily visible in a brightly lit venue. Aiming light generators also can have parallax, thereby introducing aiming errors.
In addition, there are circumstances in which the targets are tightly packed together and closely arranged relative to one another so that it is difficult for the user to accurately aim at any one selected target from among multiple targets. For example, multiple targets can be crowded or closely stacked along a one-dimensional row or column, typically in a pick list, thereby making it difficult to select any one target from the list. As another example, multiple targets can be closely spaced together in a two-dimensional array of mutually orthogonal rows and columns, typically on a packaging label, again making it difficult to select any one target from the label. Sometimes, a projected aiming light pattern is so large that it covers more than one target, again making it hard for the user to select just one target from all the covered targets.
Accordingly, there is a need to provide an apparatus for, and a method of, accurately aiming a handheld imaging reader at a selected target, without resorting to mechanical sighting elements or aiming light generators, especially for aiming the reader at a target selected from multiple targets that are closely crowded together.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.